DESCRIPTION: Human herpesvirus 7 (HHV-7) was shown to infect T cells and uses the CD4 receptor, and it has also been found to inhibit HIV-1 infection. This study proposes to characterize two viral glycoproteins that may play an important role in infection and immune modulation. The first glycoprotein is a homologue of the HHV-6 gp105 which is a target for virus-neutralizing antibodies, and the second is the M85 ORF which is a homologue of the T cells co-stimulating ligand (OX-2). Four specific aims were proposed. The first three focused on the gp105 homologue and the last on the U85 ORF. Specific aim 1 proposes to characterize the HHV-7 gp105 homologue cDNA and its protein. Specific aim 2 proposes to functionally characterize the gp105 homologue and determine whether it plays a role in viral infection and entry. The third aim proposes to construct and characterize an HHV-7 mutant lacking gp105. The last aim proposes to characterize the HHV-7 OX-2 homologue to determine whether it possesses any co-stimulatory activities. These studies should shed light on fundamental aspects of the biology and replication of HHV-7, and may contribute to the development of HHV-7 as vector for gene transfer into CD4+ T cells.